Double-walled chamber for ultra violet radiation treatment of liquids

ABSTRACT

The object of the invention is a double-walled chamber for the UV disinfection of liquids, preferably drinking water and/or waste water. It realizes a rectangular and/or square cross-sectional shape of the UV radiation chamber even at higher pressures, whereby the radiation chamber can moreover be provided with a thin-walled configuration and allows an optimal and close arrangement of UV radiators as compared with a round chamber. By applying the inventive idea, the known dead zones at the entrance are completely eliminated and an entrance turbulence is produced which runs simultaneously with the piston flow in the chamber.

FIELD OF THE INVENTION

In one of its aspects, the present invention relates to a double-walledchamber, particularly such a chamber suitable use in the ultraviolet(UV) treatment or disinfection of liquids, preferably drinking waterand/or wastewater.

DESCRIPTION OF THE PRIOR ART

UV radiation chambers are usually round boiler-like vessels throughwhich the medium to be treated flows axially. Typically, a conventionalUV radiation chamber is provided with inlet and outlet connectionslaterally at the end, partly also with axially directed outlets. It isconventional that the inlet and outlet connections, like other pressurevessels, are manufactured from round pipes, typically standardizedspecial steel pipes.

The pipe connections and/or the round boiler-like chamber or vesseltolerate high internal pressures at a use of minimal material. Thecircular shape of the boiler-like chamber or vessel is the optimalsolution. In such a round vessel there are disposed the radiationdevices which emit radiation, preferably for disinfection of the fluidmedium being treated. These are configurations (arrays) of UV radiationdevices which are inserted into a UV-permeable thin-walled quartz tubesfor protection against low temperature and humidity. With a fewexceptions, the UV radiation devices are disposed longitudinally in thetube-like UV radiation chambers, meaning that they are arranged suchthat their longitudinal axis is substantially parallel to the directionof fluid flow through the chamber or vessel.

It is normally the goal of the designer to produce the most homogeneousUV radiation field with approximately the same intensity of radiation ateach place within the chamber. Thus, the goal is to treat the liquidmolecules or “particles” such that they are disinfected in theirentirety and each molecule or “particle” individually is subjected tothe same radiation “H” (mJ/cm²; J/m²).

In a hydraulic system, the cross-flow of the radiation chamber shouldoccur, if possible, in the form of a piston flow (plug flow) along thechamber axis with an overlap by many co-running inner transversal flowcomponents, i.e., radial side flow movements. Only in this way will theindividual liquid molecules or “particles” move again to the directvicinity of the quartz cladding tubes in which the UV radiators aresituated and where there is a high radiation intensity and thedestruction of germs or microorganisms occurs nearly directly. Such aflow behavior enhances the disinfection performance of the UV treatmentdevice.

The classical ideal and laminar flow pattern is therefore not desirable.It has been noticed, however, that such a flow pattern can be achievedmore easily from a technical viewpoint than the truly “ideal” flow foran effective UV de-germination, which depends predominantly on thedesign of the chamber and the inlet and outlet conditions of the same.The occurrence of dead zones by the lateral entrance of the medium intothe cylindrical radiation chamber which are caused by too fast anduncontrollable deflection of the incoming liquid stream and a lack ofinner radial movement components often prevent the utilization of thetheoretically available radiation space (radiation duration) in thecylindrical radiation chambers.

An additional factor is that the UV radiation sources or lamps disposedalong the chamber cannot be conveniently arranged in a circular patternsuch that one can refer to a homogeneous radiation field over the crosssection and thus in the entire chamber volume. Typically, homogeneousradiation fields are only achieved with even rectangular grid arrays ofradiation sources or lamps which demand a rectangular, and preferablysquare flow cross section. Unfortunately, such an arrangement becomesproblematic, however, when a considerable pressure prevails in theinterior of the chambers, which is nearly always the case in thetreatment of drinking water.

In summary, it can be said that the usual cylindrical UV radiationchambers with the lateral inlets and axially parallel UV radiatorarrangements show three special deficiencies, namely: (i) that deadspaces are produced, (i) that a bunch of radiation sources or lampscannot be conveniently arranged evenly in a round or circular crosssection, and (iii) that the passing main flow is not overlapped by asufficient number of radial side flows.

Thus, there remains a need in the art for a chamber, vessel or treatmentdevice which obviates or mitigates at least one of the above-mentiondisadvantages of the prior art, particularly such a chamber, vessel ortreatment device for UV irradiation of fluid such was wastewater,drinking water and the like.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a novel chamber,vessel or treatment device of obviates or mitigates at least one of theabove-mentioned disadvantages of the prior art.

According in one of its aspects, the present invention provides adouble-walled chamber for the UV disinfection of liquids comprising: (i)an inlet connection; (ii) an outlet connection; (iii) an outer pipewhich encloses an inner pipe in which at least on UV radiation source isdisposed and at whose ends there is a sealing cover in which there canalso be an outlet and/or inlet opening, characterized in that theentrance of the liquid into the inner pipe with the radiation devicesoccurs through the intermediate space between the outer and inner pipe.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will be described with reference tothe accompanying drawings, wherein like reference numerals denote likeparts, and in which:

FIG. 1 a illustrates a first preferred embodiment of the presentinvention;

FIG. 1 b is a sectional view along line AB in FIG. 1 a;

FIGS. 2, 2 a, 2 b, 2 c and 2 d illustrate a second preferred embodimentof the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Thus, a preferred embodiment of the present invention is illustrated inFIGS. 1 a and 1 b, in which, for clarity, the UV radiation devices, i.e.the UV radiation sources or lamps with the cladding tubes and theradiation source or lamp hatches, are not shown. Instead, there isillustrated only the double chamber with the guidance of the passingmedium.

With reference to FIGS. 1 a and 1 b, reference numeral 1 relates to thethin-walled inner pipe of any random cross-section, e.g., a square crosssection, in which the UV radiation source or lamp configuration isdisposed. Reference numeral 2 relates an outer pressure-tight round pipewith an inlet nozzle 4 and an outlet nozzle 5. Reference numeral 3relates to the intermediate space between the two pipes 1 and 2.

The inner pipe 1 is tightly connected with the round floor 6, e.g., bywelding on the face surface at the outlet end of the chamber andcentering by means of the adapted separating wall 7 at the end side. Theinner pipe 1, which is the actual radiation chamber with the radiationdevices (again not shown for clarity), is provided at its inlet end witha circular ring of round inlet openings 8 and the baffle plate 9 at theoutlet end.

According to this preferred embodiment of the invention, the liquidmedium reaches from the inlet nozzle 4 at first into the intermediatespace 3 and from there by the circularly arranged inlet openings theinner pipe 1, which is the actual radiation chamber. Since virtually thesame pressure prevails in the intermediate space 3 and in the inner pipe1, the inner pipe 1 can be produced irrespective of its shape ofthin-walled sheet metal, which facilitates production considerably.

The outer pipe 2 is a round pipe which can be pressurized from theinside and can be produced from a relatively thin-walled material. As isshown particularly in FIG. 1 b, the medium revolves about the inner pipeof square cross section, reaches under virtually the same pressure theconforming inlet openings 8 and passes through the same in separatedpartial streams with nearly the same injection speed peripherally intothe inner pipe 1. The partial streams meet one another and mix with eachother. It is easy to see that in this way turbulence and transversemovement of the fluid is obtained when the partial streams meet eachother and that a dead space cannot occur at the inlet.

Notice should further be taken that the liquid flow will yield at thenarrow places 9 in the axial direction and that thus the “channel crosssection” will expand. It is irrelevant where precisely the inlet nozzleis located on the outer pipe. As is shown with the broken line, it couldalso be attached at reference numeral 10 from below. This may be ofrelevance when retrofitting a device, because in this way only a shortpiece needs to be opened for retrofitting the device when the inletnozzle and the outlet nozzle are close to one another. One advantage inthe arrangement of the inlet nozzle at reference numeral 10 is also thatthe intermediate space 3 is also continuously flushed.

Thus, some of the advantages of this preferred embodiment of theinvention include:

-   -   1. A non-round, e.g. square, cross section of the actual UV        radiation chamber for an optimal radiator configuration; chamber        with a thin-walled housing.    -   2. Prevention of dead spaces in the inflow region.    -   3. An outstanding swirling of the medium after the entrance into        the UV radiation chamber which is entrained by the main flow.

With reference to FIG. 2, there is illustrate another embodiment of thepresent invention.

Thus, FIG. 2 illustrates a double-walled chamber according a preferredembodiment of the present invention an exemplary technical arrangementin a slightly simplified representation. Preferably the material ofchoice is stainless steel in all parts.

Reference numeral 1 relates to the inner thin-walled pipe with a squarecross section, i.e., the actual UV radiation chamber, reference numeral2 relates to the outer pressure-tight and round pipe and referencenumeral 3 to the intermediate space between the two pipes. The wallthickness preferably is about 1.5 mm for the inner pipe and about 3 mmfor the outer round pipe. The diameter of the outer pipe is approx. 320mm. The cross sections and the arrangement of the cladding tubes 19 areshown in broken lines.

Reference numeral 4 relates to the inlet nozzle, which is arranged as aloose rotating flange. Reference numeral 6 relates to the front floorwith lead-throughs of the cladding tubes 14 into which the UV radiationsources or lamps 15 are inserted. Reference numeral 16 relates to thepress rings with a radiator cable screw connections 17 with O-ringswhich rest flat on the floor and which seal the cladding tubes 14 in apressured substantially water-tight manner to the outside.

The discharge of the irradiated water occurs via a central flangeconnection 28 with the welded stud bolts 30 in the rear chamber floor29. The inner pipe 1, which represents the actual UV radiation chamber,is provided at the inlet end with the inlet openings 8 which arearranged in a ring-like way and is welded on the inner side of the floorall around in a sealed manner to the same. The inlet nozzle 4 isslightly offset to the rear, so that the incoming liquid cannot flowmore strongly into the upper inlet openings.

At the outlet end of the double-wall chamber, the inner square pipe isfitted into the separating wall 7, which is a laser cutting with a platethickness of 1.5 mm, and welded to the same. The shape of the separatingwall 7 is shown by FIG. 2 a. The inner pipe itself consists of twolasered 1.5 mm plate halves which are canted with a defined radius andare to be welded together at an intended narrow bordering 18.

The configuration 19 shown in FIG. 2 in a sectional view of the nineprovided UV low-pressure radiation sources or lamps has been used in theconstruction in a consistent and aligned manner: starting from floor 6,in the collecting shield 20 according to FIG. 2 c and in the flow screen21 according to FIG. 2 d. The cladding tubes 14 are inserted and held inthe flow screen 21 and a baffle plate 27 is also lasered into the same.The middle radiator holder 20 has the task of receiving the claddingtubes during the installation and preventing the same from dropping andbreaking.

Once the cladding tubes have been inserted into the middle radiatorholder 20, they will always find their fixing device in the flow screen21 when they are pushed in further. Components 20 and 21 are also lasercuts. They can be produced easily, precisely and cheaply. The importantaspect is, which needs to be mentioned specifically, that the mountingof the cladding tubes in the flow screen is made free from play so thatthey cannot vibrate, which could lead to destruction thereof.

The openings 22 in the flow screen 21 according to FIG. 2 d comprisebending clips 23 which can be bent out to such an extent that thecladding tubes can latch in with the round end 24 practically free fromplay during the insertion and will thus sit tightly. The welding of theflow screen 21 occurs by turning the welding clips 25 by 90°, whereuponone can weld them at both sides with a weld in the tube and can thusprevent crevice corrosion. In the case of the middle radiator holder 20,the clips 26 are bent by 90°, a bolt each is welded on to the same,which bolt latches into the provided hole when in position and is weldedon consistently from the outside with an HV weld in order to preventcrevice corrosion in this manner. The openings 31 are used for emptying.

With the nine low-pressure radiators with an output of 230 W and a 253.7nm radiation flux of 80 W one can still disinfect approx. 60 m3/h ofcleared and pre-filtered waste water with a transmission of only 0.55%by 1 cm according to EU directives for bathing water.

While this invention has been described with reference to illustrativeembodiments and examples, the description is not intended to beconstrued in a limiting sense. Thus, various modifications of theillustrative embodiments, as well as other embodiments of the invention,will be apparent to persons skilled in the art upon reference to thisdescription. It is therefore contemplated that the appended claims willcover any such modifications or embodiments.

All publications, patents and patent applications referred to herein areincorporated by reference in their entirety to the same extent as ifeach individual publication, patent or patent application wasspecifically and individually indicated to be incorporated by referencein its entirety

1. A double-walled chamber for the UV disinfection of liquidscomprising: (i) an inlet connection; (ii) an outlet connection; (iii) anouter pipe which encloses an inner pipe in which at least on UVradiation source is disposed and at whose ends there is a sealing coverin which there can also be an outlet and/or inlet opening, characterizedin that the entrance of the liquid into the inner pipe with theradiation devices occurs through the intermediate space between theouter and inner pipe.
 2. The double-walled chamber defined in claim 1,wherein the outer pipe is a circular pipe.
 3. The double-walled chamberdefined in claim 1, wherein the inner pipe has a rectangular crosssection.
 4. The double-walled chamber defined in claim 1, wherein theinner pipe has a circular cross section.
 5. The double-walled chamberdefined in claim 1, wherein at the outer pipe is non-circular.
 6. Thedouble-walled chamber defined in claim 1 wherein at the inner pipe isnon-circular.
 7. The double-walled chamber defined in claim 1, whereinat the inner pipe is non-rectangular.